docs: def verify_cert(self):
          '''
          Checks that the provided cert and key are valid and usable
          '''
          log.debug('Verifying the %s certificate, keyfile: %s',
                    self.certificate, self.keyfile)
          try:
              ssl.create_default_context().load_cert_chain(self.certificate, keyfile=self.keyfile)
          except ssl.SSLError:
              error_string = 'SSL certificate and key do not match'
              log.error(error_string)
              raise SSLMismatchException(error_string)
          except IOError:
              log.error('Unable to open either certificate or key file')
              raise
          log.debug('Certificate looks good.')